3of 9Pemex's daily production has slid by almost 1 million barrels since its 2004 peak. President Enrique Pena Nieto signed legislation in 2013 to let private producers pump crude in Mexico for the first time in 76 years.Photo: Susana Gonzalez

4of 9Lights illuminate a section of Petroleos Mexicanos (Pemex) Pol-A Platform complex, located on the continental shelf in the Gulf of Mexico, 70 kilometers offshore from Ciudad del Carmen, Mexico, on Friday, March 28, 2014. "Production is stable and we foresee production reaching our target levels above 2.5 million barrels per day,â Pemex chief executive officer Emilio Lozoya said in an interview last week. Photographer: Susana Gonzalez/BloombergPhoto: Susana Gonzalez

5of 9The sun sets over a connecting bridge at the Petroleos Mexicanos (Pemex) Pol-A Platform complex, located on the continental shelf in the Gulf of Mexico, 70 kilometers offshore from Ciudad del Carmen, Mexico, on Friday, March 28, 2014. "Production is stable and we foresee production reaching our target levels above 2.5 million barrels per day,â Pemex chief executive officer Emilio Lozoya said in an interview last week. Photographer: Susana Gonzalez/BloombergPhoto: Susana Gonzalez

6of 9A worker inspects the pressure of the valves in a section of the Petroleos Mexicanos (Pemex) Pol-A Platform complex, located on the continental shelf in the Gulf of Mexico, 70 kilometers offshore from Ciudad del Carmen, Mexico, on Friday, March 28, 2014. "Production is stable and we foresee production reaching our target levels above 2.5 million barrels per day,â Pemex chief executive officer Emilio Lozoya said in an interview last week. Photographer: Susana Gonzalez/BloombergPhoto: Susana Gonzalez

7of 9Gas flares at a burner tower, right, on the Petroleos Mexicanos (Pemex) Pol-A Platform complex, located on the continental shelf in the Gulf of Mexico, 70 kilometers offshore from Ciudad del Carmen, Mexico, on Saturday, March 29, 2014. "Production is stable and we foresee production reaching our target levels above 2.5 million barrels per day,â Pemex chief executive officer Emilio Lozoya said in an interview last week. Photographer: Susana Gonzalez/BloombergPhoto: Susana Gonzalez

8of 9A worker from Oceanografia SA walks down a set of stairs on a section of the Petroleos Mexicanos (Pemex) Pol-A Platform complex, located on the continental shelf in the Gulf of Mexico, 70 kilometers offshore from Ciudad del Carmen, Mexico, on Friday, March 28, 2014. "Production is stable and we foresee production reaching our target levels above 2.5 million barrels per day,â Pemex chief executive officer Emilio Lozoya said in an interview last week. Photographer: Susana Gonzalez/BloombergPhoto: Susana Gonzalez

9of 9A group of workers walk up a set of stairs after arriving to work in the early morning at the Petroleos Mexicanos (Pemex) Pol-A Platform complex, located on the continental shelf in the Gulf of Mexico, 70 kilometers offshore from Ciudad del Carmen, Mexico, on Saturday, March 29, 2014. "Production is stable and we foresee production reaching our target levels above 2.5 million barrels per day,â Pemex chief executive officer Emilio Lozoya said in an interview last week. Photographer: Susana Gonzalez/BloombergPhoto: Susana Gonzalez

Mexico is headed for its lowest annual oil production on record as state-owned Petroleos Mexicanos prepares for an influx of foreign investment.

Mexico produced 2.35 million daily barrels of oil in December through Sunday, according to data the Mexico City-based company posted online Wednesday. Based on that preliminary rate and averaged with other monthly data for the year, Pemex produced 2.43 million barrels a day in 2014, for a 10th consecutive annual output decline.

That figure, which may be further cut to reflect measurement problems announced in August, would be the lowest annual output since at least 1990, when the government began releasing data. Daily production has slid by almost1 million barrels since a 2004 peak.

Mexico's Energy Ministry sees outside investment ending declines in the world's ninth-largest oil producer, with output expected to increase 500,000 barrels by 2018. President Enrique Pena Nieto signed legislation in 2013 to allow private producers such as Chevron Corp. and Exxon Mobil Corp. to pump crude in Mexico for the first time in 76 years.

Pemex originally forecast production of 2.5 million barrels a day in 2014, a figure that was revised to 2.35 million in August to reflect water content and inaccurate measuring systems.

Pemex forecasts oil production will reach 2.4 million barrels per day in 2015, according to exploration and production director Gustavo Hernandez. The company may revise historic production figures from the first six months of the year to reflect inaccurate measurements, he said.